Roof-jack for a metallurgical furnace



Oct. 19, 1965 J. c. WINTERSTEEN ROOF-JACK FOR A METALLURGICAL FURNACEFiled Jan. 7, 1963 N MW 3 Wm 3 E w 5 AZ mm n 321 w A t..... 20: 0 N H 0J mw Mm mm vw MM fi i 1 I 1 1 GM], 1 I I I I /N\ \u E m I I I I I I I Il I l I I I I I I IICW'IIIHHU -mfifl A "El United States Patent C)3,212,466 ROOF-JACK FOR A METALLURGICAL FURNACE John C. Wintersteen,Munhall, Pa., assignor to United States Steel Corporation, a corporationof New Jersey Filed Jan. 7, 1963, Ser. No. 249,666 4 Claims. (Cl.110-99) The present invention relates generally to metallurgical furnaceequipment and more particularly to an improved roof-jack especiallysuitable for use with an open hearth furnace.

A modern open hearth furnace is usually constructed with an archedrefractory brick roof which is supported by the walls of the furnace. Asteel framework of slabs, plates and structural shapes rigidly tiedtogether by transversely extending overhead beams supports the furnacebottom and walls.

The refractory bricks of which the roof is made are subjected torelatively high temperatures during operation of the furnace and whensubjected to such temperatures over a period of time the bricks undergoa physical change which is known in the art as growt During growth thephysical dimensions of the brick increase or grow. At the same time suchgrowth is taking place, the thickness of the roof arch graduallydiminishes because of erosion, spalling and melting of the underside ofthe roof which is exposed to the combined influences of heat and gasesin the interior of the furnace. Simultaneous growt of the roof brick anddecrease of the thickness of the roof arch cause the roof-to deviatefrom its original design contour and fail prematurely.

In order to minimize the detrimental effects of the growthcharacteristic of roof brick, a hold-down system is utilized. Prior tomy invention a typical hold-down system usually included a plurality ofshort steel beams which were disposed horizontally on the top of thearched roof in spaced parallel relation extending along the length ofthe roof. The steel beams were braced against the furnace roof arch byrigid steel posts which were interposed between the beams and theoverhead beams of the furnace framework. The bottoms of the posts werebolted to the hold-down beams while the upper ends thereof were rigidlyattached to the overhead framework beams by welding. Thus, afterassembly, the steel posts provided a rigid connection between thehold-down beams and the furnace steel framework.

The present practice of building or rebuilding the roof of an openhearth furnace involves laying the roof arch on a form which issupported from below and which is removed when the roof arch iscompleted. After the roof arch has been completed, the hold-down beamsare laid on the top side of the arch in predetermined locations. Thenthe hold-down posts are bolted to the hold-down beams and welded to thefurnace steel framework.

The hold-down beams and posts and their attachment to the furnace steelframework as arranged prior to my invention constituted a rigidhold-down system. Due to the rigidity of this hold-down system, theforces generated by thermal expansion of the roof arch during operationof the furnace and the growt of the refractory brick making up the roofarch were transmitted into the furnace steel framework and causeddeflection or bending of the components of the furnace steel framework.This deflection or bending of the furnace framework tended to lessen 12in the front and back wall.

3,212,466 Patented Oct. 19, 1965 support of the furnace refractorymaterials and consequently resulted in accelerated furnace failure.

The stability and strength of an arched open hearth furnace roof is alsoinfluenced by the load or weight supported by the roof as well as thecontour of the arch. Since the roof arch hold-down system of the priorart was rigid there was no adjustment possible to compensate for thedecreasing thickness of and dead load carried by the roof arch whichoccurred as a result of erosion, spalling, and melting.

After a furnace equipped with the prior art hold-down system had been inoperation for a period of time and the roof arch materials haddeteriorated to the extent that rebuilding or replacement of the furnaceroof was necessary, it was found that the upper furnace steel framework,to which the hold-down posts were welded, although still satisfactoryfor further service, was often bent and warped so that the alignment andlengths of the original hold-down posts did not agree perfectly with thelocations and lengths of posts required when the roof arch and hold-downbeams were replaced in the original locations after the roof wasrebuilt. When this occurred it was necessary to chip the posts from thesupporting steel framework and re-weld them to suit the replacement archand the positions of the hold-down beams thereon. This requiredextending the down-time of the furnace and increased rebuilding costs.

It is, accordingly, the primary object of my invention to provide animproved roof-jack for a metallurgical furnace having a refractory roofarch which when installed between the hold-down beams and the uppersteel frame work of the furnace will permit a limited amount ofexpansion and growth of the refractory roof arch and at the same timeapply an adjustable and predetermined restraining force to thermalexpansion of the roof arch.

Another object of my invention is to provide an improved furnaceroof-jack of the character described which is capable of automaticallyapplying a gradually increasing resistance to the growth of therefractory roof arch so that the loss of thickness of the arch andconsequent loss of dead weight bearing on the arch will be compensatedfor automatically.

It is a further object of my invention to provide an improved furnaceroof-jack of the character described which can be fastened to thehold-down beams in a manner which will permit easy adjustment along thebeam due to misalignment or other reasons.

These and other objects will become more apparent after referring to thefollowing specification and attached drawings, in which:

FIGURE 1 is a cross sectional view of an open hearth furnace having theroof-jacks of my invention installed thereon;

FIGURE 2 is an enlarged elevational view of the roofjack of theinvention;

FIGURE 3 is a vertical sectional view of the roof-jack of the invention;and

FIGURE 4 is a partial elevational view turned from FIGURE 2.

Referring more particularly to the drawings, reference numeral 2designates, generally, an open hearth furnace having a refractory frontwall 4, back wall 6, bottom 8, and an arched refractory roof 10supported by skewbacks The refractory walls and bottom of the furnaceare usppor-ted by a steel framework 14 which includes an upper portionconsisting of beams 16 extending transversely above the roof 10. Aseries of hold-down beams 18 are disposed in spaced parallel relation onthe arched roof extending lengthwise thereof. At least one roof-jack ofthe invention, indicated generally by reference numeral 20, isinterposed between each hold-down beam and the upper portion of theframework 14.1

As best shown in FIGURE 3, the roof-jack 20 of the invention includes anextensible post portion made up of lower and upper hollow cylinders 22and 24, respectively, disposed in vertical alignment. The adjacent endsof the cylinders 22 and 24 are externally threaded and are adjustablyjoined by means of a coupling 26. A plate 28 is welded or otherwiserigidly secured across the bottom end of lower cylinder 22.

A sleeve 30 is telescoped on the upper end of cylinder 24 and isprovided with an internal collar 32 welded or otherwise securelyfastened in its upper end. A bolt 34 is disposed with its head welded inthe upper end of the cylinder 24 and its shaft extending upwardlythrough the sleeve 30 and projecting outwardly thereof. A helicalcompression spring 36 is circumferentially disposed around the shaft ofbolt 34 in the sleeve 30 with one end thereof bearing against the upperend of cylinder 24 and its other end bearing against the collar 32. Theprojecting end of the shaft of the bolt 34 is threaded and has a nut 38adjustably threaded thereon bearing against the collar 32. The spring 36and sleeve 30 thus constitute a spring cushion which may be adjusted tothe desired degree of tension to resiliently maintain the sleeve intelescoping relation with the extensible post formed by the cylinders 22and 24 and the coupling 26.

A predetermined initial compression is created in the jack 20 byadjusting the position of the nut 38 while upper cylinder 24 isrestrained from turning. Length adjustment of the extensible postportion is achieved by rotating cylinder 22 or cylinder 24, or bothcylinders, while coupling 26 is restrained from turning.

Two pairs of clips 40 are used to attach the base 28 of the jack to oneof the hold-down beams 18, as shown in FIGURES 2, 3 and 4. Each of theclips 40 is formed with an upright portion 42 and a hook portion 44which engages the upper flange of the hold-down beam and the base plate28, as best shown in FIGURE 4. The upright portions 42 of each pair ofclips 40 are provided with aligned holes for accommodating a bolt 48which is secured by a nut 50 and serves to lock the clips 40 inengagement with the plate 28 and the flanges of the holddown beam 18.

Before installation, the jack 20 of the invention is assembled bythreading the cylinders 22 and 24 into opposi-te ends of the coupling26. The sleeve 30 containing the helical spring 36 is telescoped overthe free end of the upper cylinder 24 so that the spring surrounds theshaft of the bolt 34, which was previously aflixed in the upper end ofthe cylinder 24 as described above. The end of the bolt shaft passesthrough the collar 32 which is welded on the inside of the sleeve 30.The nut 38 is then threaded on the projecting end of the shaft of thebolt 34 to maintain the sleeve on the cylinder 24. The sleeve 30 is thenwelded adjacent its upper end to the web of one of the beams 16 in theupper part of the framework 14. Then, while the coupling 26 is heldunder restraint the lower cylinder 22 is threaded outwardly of thecoupling until the plate 28 on the bottom of the cylinder rests on theupper surface of one of the hold-down beams 18. If desired, a hole 52may be provided through the body of each of the cylinders 22 and 24adjacent the adjoining ends thereof. The holes 52 in each cylinder arelocated at a distance away from the end of the cylinder which is equalto the minimum threaded engagement desired with the coupling 26 so thatdisengagement of the cylinders and coupling can be easily avoided.

After the bottom of the cylinder 22 is placed on the hold-down beam,clips 40 are affixed to the plate 28 on opposite sides of the cylinderin engagement with the flange of the hold-down beam so as to secure thejack to the hold-down beam. After the jack has thus been secured to thehold-down beam, the nut 38 is adjusted to compress the spring 36sufliciently so that the jack is under compression between the upperframework 14 and the hold-down beam.

Each of the jacks can be individually adjusted to meet variousconditions of arch size, expected thermal expansion of the roof arch,and the growth characteristics of the refractory brick making up theroof arch. Then, as the roof arch thickness decreases and as therefractory roof material grows, the increasing deflection of the helicalspring 36 in each of the jacks will automatically compensate for theloss in dead weight of the arch material, thereby helping the roof archto maintain its strength. The cylinders 22 and 24 and their threadedengagement with the coupling permits minute length adjustment of eachjack. The ease with which the lower cylinder 22 can be removed from thejack and the easily removable clip arrangement connecting the jack tothe hold-down beam facilitates the replacement of hold-down beams whenit is necessary to rebuild the furnace roof. The use of the removableclips 40 to secure the base of the jack to the hold-down beam alsopermits some variation in the positioning of the jack along the lengthof the hold-down beam.

While one embodiment of my invention has been shown and described, itwill be apparent that other adaptations and modifications may be madewithout departing from the scope of the fol-lowing claims.

I claim:

1. The combination with an arched furnace roof and an overheadstructural framework extending transversely thereabove, of a pluralityof jacks connected to said framework and bearing downwardly on saidroof, each jack comprising an extensible post and a pre-loaded springcushion alined with the post, each of said jacks being disposed insubstantially upright position between said overhead framework and saidroof whereby said preloaded spring cushions exert force pressing down onsaid roof from said overhead framework.

2. The combination defined by claim 1 characterized by each of saidextensible posts comprising a pair of elongated hollow cylindersdisposed in longitudinal alignment with their adjacent ends adjustablythreaded into opposite ends of a coupling whereby said cylinders can bemoved axially toward and away from each other.

3. The combination defined by claim 1 characterized by said cushionincluding a sleeve telescoped on said extensible post and projectingcoaxial therewith, and spring means in said sleeve resilientlymaintaining said sleeve in telescoping relation with said post.

4. In an open hearth furnace having an arched roof, a plurality ofspaced beams extending along said roof, and a structural frameworkextending transversely above said roof, the improvement therewith of aplurality of roof jacks connected to said framework and bearing againstsaid beams, each of said roof jacks comprising a pair of upper and lowerelongated hollow cylinders disposed in longitudinal alignment betweenone of said beams and said framework with their adjacent ends adjusablythreaded into opposite ends of a coupling whereby said cylinders can bemoved axially toward and away from each other, a sleeve telescoped onthe free end of the upper cylinder and projecting coaxial therewith, ashaft having a threaded end disposed concentrically in said sleeve withits threaded end projecting outwardly of said sleeve and its other endanchored in the upper end of the upper cylinder, an internal collarrigidly disposed in the upper end of said sleeve surrounding said shaft,a helical compression spring circumferentially disposed around saidshaft in said sleeve with one end bearing against the upper end of theupper cylinder and its other end bearing against said collar, a nutadjustably threaded on the projecting end of said shaft and bearingagainst said collar to thereby resiliently maintain said sleeve intelescoping relation with the upper cylinder, said sleeve being rigidlyfastened to said framework adjacent its upper end, and means removablyconnecting the lower cylinder to said one of said beams.

References Cited by the Examiner 11/53 Honig 110-99 1/55 Davies.

10/59 Suozzo 267-1 1/ 62 Hosbein et a1. 110-99 1/63 Correc 363-46 XFOREIGN PATENTS 7/52 Great Britain.

OTHER REFERENCES German printed application No. 1,078,271, March 24,

JAMES W. WESTHAVER, Primary Examiner.

15 PERCY L. PATRICK, FREDERICK KETTERER,

Examiners,

1. THE COMBINATION WITH AN ARCHED FURNACE ROOF AND AN OVERHEAD STRUCTURAL FRAMEWORK EXTENDING TRANSVERSELY THEREABOVE, OF A PLURALITY OF JACKS CONNECTED TO SAID FRAMEWORK AND BEARING DOWNWARDLY ON SAID ROOF, EACH JACK COMPRISING AN EXTENSIBLE POST AND A PRE-LOADED SPRING CUSHION ALINED WITH THE POST, EACH OF SAID JACKS BEING DISPOSED IN SUBSTANTIALLY UPRIGHT POSITION BETWEEN OVERHEAD FRAMEWORK AND SAID ROOF WHEREBY SAID PRELOADED SPRING CUSHIONS EXERT FORCE PRESSING DOWN ON SAID ROOF FROM SAID OVERHEAD FRAMEWORK. 